Ammonia treatment of tobacco has been employed in the past, principally as a means to displace and effect release of nicotine. Denicotinization processes have been described. Representative of such processes are those disclosed in U.S. Pat. Nos. 1,640,298 (Sartig), 1,719,291 (Federmann), 2,136,485 (Berka et al), 2,162,738 (McCoy), 2,227,863 (Rhodes) and 3,742,962 (Brochot). In some procedures, the temperature is elevated very little, in others at least to 100.degree. C., but in every instance there is removal of components, notably nicotine, from the tobacco and generally speaking no effort is made to maintain the presence of ammonia without dilution (as by steam) or removal (as by sweeping with air or steam).
Ammonia was disclosed as an expansion agent for tobacco by Armstrong et al., U.S. Pat. No. 3,771,533. The process involves impregnation of tobacco with liquid or gaseous ammonia and exposure of the resulting tobacco to very rapid heating in unconfined (open vessel) conditions to bring about expansion with release of the ammonia. The reasons for a need for expanded tobacco are well known.
Deszyck, U.S. Pat. No. 3,760,815 discloses the use of ammonium salts of carboxylic acids, made alkaline with added ammonium hydroxide, to treat a slurry of tobacco parts to release pectins therefrom which will serve as a binder for reconstituted tobacco sheet prepared from the composite. The slurry may be heated during the pectin release step. The cast sheet is then dried with loss of the ammonia together with the excess water.
In all the prior disclosures such as those mentioned above, either the tobacco is not heated when it is maintained in contact with ammonia, or it is heated in circumstances which dictate either the rapid disappearance of ammonia or its considerable dilution, as with water or a gas (air, steam).